Fix Dockerfile.spark for CUDA 13.0 compatibility

- Use nvidia/cuda:12.4.0-runtime-ubuntu22.04 base image
- Install PyTorch with CUDA 12.4 wheels (compatible with CUDA 13.0 driver)
- Build Python dependencies properly for ARM64

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker/Dockerfile.spark

@@ -1,17 +1,27 @@
-# GPU-enabled Dockerfile for DGX Spark deployment (ARM64/aarch64)
-# Using NVIDIA NGC PyTorch image which supports ARM64
-FROM nvcr.io/nvidia/pytorch:24.01-py3
+# GPU-enabled Dockerfile for DGX Spark deployment (ARM64/aarch64 + CUDA 13.0)
+FROM nvidia/cuda:12.4.0-runtime-ubuntu22.04
 
-# Install additional system dependencies
+# Install Python and system dependencies
 RUN apt-get update && apt-get install -y \
+    python3 \
+    python3-pip \
+    python3-dev \
     curl \
-    && rm -rf /var/lib/apt/lists/*
+    build-essential \
+    && rm -rf /var/lib/apt/lists/* \
+    && ln -s /usr/bin/python3 /usr/bin/python
 
 WORKDIR /app
 
-# Copy and install Python requirements
+# Install PyTorch with CUDA support first (before other requirements)
+# Using CUDA 12.4 wheels which are compatible with CUDA 13.0 driver
+RUN pip3 install --no-cache-dir \
+    torch \
+    --index-url https://download.pytorch.org/whl/cu124
+
+# Copy and install remaining Python requirements
 COPY requirements.txt .
-RUN pip install --no-cache-dir -r requirements.txt
+RUN pip3 install --no-cache-dir -r requirements.txt
 
 # Copy backend code
 COPY backend/ ./backend/